Mini-joysticks are generally:    positioned on the lateral side, towards the outside with respect to the seats of the pilots; and    decoupled in their movement. Thus any action on one joystick does not give rise to movement of the opposite joystick.
The result of this design is that the movements made during flight, by a first pilot who is piloting the aircraft, on his joystick, can in certain circumstances be difficult or even impossible to perceive by the second pilot who is not doing the piloting.
The only way that the second pilot (the one not doing the piloting) can try to perceive the movement controlled by the first pilot is for him to change the direction in which he is looking or to lean forwards, which results in a loss of near and external vision.
This solution is not therefore entirely satisfactory.